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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Brand Name
Diuril
Generic Name
Chlorothiazide
Active Ingredient
ChlorothiazideCategory
Thiazide Diuretic [EPC]
Salt Form
Sodium
Variants
1
Different strengths and dosage forms
| Strength | Form | Route | NDC |
|---|---|---|---|
| 250 mg/5mL | SUSPENSION | ORAL | 65649-311 |
Detailed information about Diuril
This page is for informational purposes only and does not replace medical advice. Before using any prescription or over-the-counter medication for Diuril, you must consult a qualified healthcare professional.
Chlorothiazide is a foundational thiazide diuretic used to manage hypertension and edema. It works by inhibiting sodium reabsorption in the kidneys to promote fluid excretion.
The dosage of Chlorothiazide is highly individualized based on the patient's response and the condition being treated. According to clinical guidelines, the goal is to achieve the maximum therapeutic effect with the lowest possible dose.
Chlorothiazide is one of the few thiazide diuretics with well-established pediatric dosing guidelines, often utilized in the neonatal intensive care unit (NICU) or for children with congenital heart defects.
Chlorothiazide loses its efficacy as kidney function declines. In patients with a creatinine clearance (CrCl) of less than 30 mL/min, thiazide diuretics are generally considered ineffective. In such cases, "loop diuretics" (like furosemide) are usually preferred. If used in patients with mild renal impairment, frequent monitoring of BUN and creatinine is required.
Use with extreme caution in patients with impaired hepatic function or progressive liver disease. Minor alterations of fluid and electrolyte balance may precipitate hepatic coma (a loss of brain function due to liver failure).
Older adults should generally start at the lower end of the dosing range (e.g., 125 mg for hypertension). The elderly are more susceptible to dehydration, orthostatic hypotension (dizziness upon standing), and electrolyte depletion. Clinical data suggests that lower doses are often sufficient for blood pressure control in this population.
If you miss a dose, take it as soon as you remember. However, if it is almost time for your next scheduled dose, skip the missed dose and resume your regular schedule. Do not double the dose to catch up, as this increases the risk of dehydration and electrolyte disturbances.
Signs of a Chlorothiazide overdose primarily relate to excessive loss of fluid and electrolytes. Symptoms may include:
In the event of a suspected overdose, contact your local poison control center or seek emergency medical attention immediately. Treatment is generally supportive, focusing on replacing fluids and correcting electrolyte imbalances.
> Important: Follow your healthcare provider's dosing instructions exactly. Do not adjust your dose or stop taking this medication without medical guidance, as sudden changes can cause your blood pressure to spike or fluid to return rapidly.
Most patients tolerate Chlorothiazide well, but because it alters the body's chemistry, some side effects are common. These are often dose-related and may improve as the body adjusts to the medication.
> Warning: Stop taking Chlorothiazide and call your doctor immediately if you experience any of these symptoms, which may indicate a severe electrolyte imbalance or allergic reaction.
Prolonged use of Chlorothiazide requires ongoing medical supervision. Long-term effects can include:
No FDA black box warnings for Chlorothiazide. Unlike some more potent diuretics, Chlorothiazide does not carry a boxed warning, but its potential for profound diuresis and electrolyte depletion is considered a major clinical precaution.
Report any unusual symptoms to your healthcare provider. Regular blood tests are essential to catch side effects before they become serious.
Chlorothiazide is a potent medication that requires careful monitoring. Patients must be aware that while it treats the symptoms of high blood pressure and edema, it does not "cure" these conditions. Therapy is often lifelong. The most critical safety concern is the maintenance of fluid and electrolyte balance. Dehydration and mineral loss can occur rapidly, especially during hot weather, bouts of vomiting or diarrhea, or periods of intense exercise.
As of 2026, there are no FDA black box warnings for Chlorothiazide. However, the FDA emphasizes that this drug should be used only after a thorough clinical assessment of the patient's renal and hepatic status.
Your healthcare provider will schedule regular laboratory tests to ensure the medication is working safely. These typically include:
Chlorothiazide can cause dizziness, blurred vision, or lightheadedness, particularly during the first few days of treatment or when the dose is increased. Do not drive, operate heavy machinery, or engage in dangerous activities until you know how this medication affects you. If you feel faint, sit or lie down immediately.
Alcohol consumption should be limited while taking Chlorothiazide. Alcohol can enhance the blood pressure-lowering effect of the drug, significantly increasing the risk of orthostatic hypotension (severe dizziness upon standing). This can lead to falls and injuries.
Do not stop taking Chlorothiazide abruptly. For patients with hypertension, stopping the medication can lead to a "rebound" effect where blood pressure rises rapidly. For patients with heart failure, stopping the drug can cause a sudden buildup of fluid in the lungs (pulmonary edema), which is a medical emergency. If the drug must be stopped, your doctor will provide a tapering schedule.
> Important: Discuss all your medical conditions, especially kidney disease, liver disease, and diabetes, with your healthcare provider before starting Chlorothiazide.
Chlorothiazide can interfere with several diagnostic tests:
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking. A complete list helps prevent dangerous interactions.
There are specific circumstances where Chlorothiazide must NEVER be used because the risks far outweigh any potential benefits:
In these situations, a healthcare provider will perform a careful risk-benefit analysis and may choose an alternative medication:
Patients should be aware of cross-sensitivity with other drugs. If you have had a reaction to the following, you may be at risk when taking Chlorothiazide:
> Important: Your healthcare provider will evaluate your complete medical history, including all past allergies and kidney function tests, before prescribing Chlorothiazide.
Chlorothiazide is categorized by the FDA as Pregnancy Category C. This means that animal reproduction studies have shown an adverse effect on the fetus, and there are no adequate and well-controlled studies in humans.
Chlorothiazide is excreted in human milk. Because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. High doses of thiazides can also suppress lactation by inducing diuresis and reducing the hormones needed for milk production.
Chlorothiazide is frequently used in pediatric medicine, particularly for children with heart failure or those who have developed fluid retention from other medications.
Clinical studies of Chlorothiazide did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. However, clinical experience has identified several concerns:
In patients with renal disease, thiazides may precipitate azotemia. Cumulative effects of the drug may develop in patients with impaired renal function. If progressive renal impairment becomes evident, as indicated by a rising nonprotein nitrogen or blood urea nitrogen (BUN), a careful reappraisal of therapy is necessary with consideration given to withholding or discontinuing diuretic therapy.
Thiazides should be used with caution in patients with impaired hepatic function or progressive liver disease, since minor alterations of fluid and electrolyte balance may precipitate hepatic coma. Many clinicians prefer to use Chlorothiazide only in a hospital setting for patients with severe cirrhosis.
> Important: Special populations require individualized medical assessment and more frequent laboratory monitoring.
Chlorothiazide exerts its effect by interfering with the renal tubular mechanism of electrolyte reabsorption. The primary site of action is the Distal Convoluted Tubule (DCT). It specifically inhibits the Na+/Cl- cotransporter (NCC) on the luminal membrane of the epithelial cells. By blocking this transporter, Chlorothiazide increases the excretion of sodium and chloride in approximately equivalent amounts.
Natriuresis (sodium loss) is accompanied by a secondary loss of potassium and bicarbonate. It also reduces the glomerular filtration rate (GFR) slightly when initiated. A unique secondary effect of thiazides is the promotion of calcium reabsorption in the distal tubule, which is the opposite effect of loop diuretics (which increase calcium loss).
| Parameter | Value |
|---|---|
| Bioavailability | 9% - 25% (Oral) |
| Protein Binding | 20% - 80% (Albumin) |
| Half-life | 1.5 - 2.5 hours |
| Tmax (Time to peak) | 4 hours (Oral) |
| Metabolism | Not metabolized (Excreted unchanged) |
| Excretion | Renal (>95%) |
Chlorothiazide is the prototypical member of the Thiazide Diuretic class. Related medications include Hydrochlorothiazide, Chlorthalidone (a thiazide-like diuretic), and Indapamide. It is classified under the ATC code C03AA04.
Common questions about Diuril
Chlorothiazide is primarily used to treat high blood pressure (hypertension) and fluid retention, also known as edema. It is commonly prescribed for patients with congestive heart failure, liver cirrhosis, or kidney disorders to help the body eliminate excess salt and water. By reducing fluid buildup, it can help relieve symptoms like shortness of breath and swelling in the ankles or legs. Additionally, it is used as a foundational treatment for hypertension to reduce the risk of strokes and heart attacks. Your doctor may prescribe it alone or in combination with other medications depending on your specific health needs.
The most common side effects of Chlorothiazide include dizziness, lightheadedness, and headache, particularly when you first start the medication or stand up quickly. Because it is a diuretic, increased frequency of urination is expected and is the primary way the drug works. Some patients also experience mild stomach upset, such as nausea or cramping. More importantly, it can cause changes in your blood chemistry, leading to low potassium or low sodium levels. If you experience severe muscle weakness, confusion, or an irregular heartbeat, you should contact your healthcare provider immediately as these may be signs of a serious electrolyte imbalance.
It is generally advised to limit or avoid alcohol consumption while taking Chlorothiazide. Alcohol has a natural blood pressure-lowering effect and can act as a mild diuretic itself. When combined with Chlorothiazide, alcohol can significantly increase the risk of orthostatic hypotension, which is a sudden drop in blood pressure when you stand up. This can lead to severe dizziness, lightheadedness, and even fainting, which increases the risk of falls and injury. If you choose to drink, do so in moderation and only after discussing the risks with your doctor.
Chlorothiazide is classified as FDA Pregnancy Category C, meaning its safety has not been fully established in human pregnancy. It is known to cross the placenta and can potentially cause issues for the newborn, such as jaundice or a low blood platelet count. Generally, healthcare providers avoid using diuretics for the routine swelling associated with pregnancy. It is only prescribed if the potential benefits to the mother outweigh the potential risks to the developing fetus. If you are pregnant or planning to become pregnant, you must discuss alternative treatments for blood pressure or edema with your healthcare provider.
The time it takes for Chlorothiazide to work depends on the form you are taking and the condition being treated. For the oral tablet or suspension, you will typically notice an increase in urination within 2 hours, with the peak effect occurring around 4 hours after the dose. For the intravenous (IV) form, the effect begins much faster, usually within 15 minutes. While the diuretic effect (fluid loss) is almost immediate, the full blood pressure-lowering effect for hypertension may take 3 to 4 weeks of consistent use to become fully apparent. It is important to keep taking the medication even if you do not feel an immediate difference in your blood pressure.
You should never stop taking Chlorothiazide suddenly without first consulting your healthcare provider. Abruptly discontinuing the medication can cause a 'rebound' effect, where your blood pressure may rise rapidly to dangerous levels. For those taking it for heart failure or edema, stopping the drug can lead to a sudden and severe accumulation of fluid, which might cause difficulty breathing or a worsening of heart symptoms. If you need to stop the medication due to side effects or other reasons, your doctor will likely provide a schedule to gradually reduce your dose to ensure your safety.
If you miss a dose of Chlorothiazide, take it as soon as you remember. However, if it is already late in the day or close to the time for your next dose, it is usually better to skip the missed dose and return to your regular schedule. Taking the medication too late in the evening can cause you to wake up multiple times during the night to urinate, which can disrupt your sleep. Never take two doses at once to make up for a missed one, as this increases the risk of dehydration and electrolyte imbalances. If you are unsure, contact your pharmacist or doctor for guidance.
Chlorothiazide typically causes weight loss, not weight gain, because it removes excess fluid from the body. In fact, doctors often ask patients with heart failure to monitor their weight daily while taking this medication; a sudden decrease in weight usually indicates the drug is successfully removing fluid. If you experience sudden weight gain while taking Chlorothiazide, it may be a sign that your condition (such as heart failure) is worsening and that the medication is not removing enough fluid. In such cases, you should contact your doctor immediately, as your dosage may need adjustment.
Chlorothiazide can interact with many other medications, so it is vital to provide your doctor with a full list of everything you take. It is often safely combined with other blood pressure medications, but some combinations require extra caution. For example, taking it with Lithium can lead to lithium toxicity, and taking it with Digoxin can increase the risk of heart rhythm problems if your potassium gets too low. Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen can also make Chlorothiazide less effective and harder on your kidneys. Always consult your healthcare provider before starting any new over-the-counter drugs or supplements.
Yes, Chlorothiazide is available as a generic medication, which is typically much less expensive than brand-name versions. The generic version is bioequivalent to the brand-name drug Diuril, meaning it has the same active ingredient and works the same way in the body. It is available as an oral suspension and an injectable powder. While the oral tablets are less common today (as many patients have been moved to hydrochlorothiazide), the generic liquid form remains a standard treatment, especially in pediatric care. Check with your pharmacist to see if a generic version is the most cost-effective option for your prescription.
Other drugs with the same active ingredient (Chlorothiazide)